INTRODUCTION TO ECOLOGY
AND ENVIRONMENTAL
What is ecology?
origin of word: oikos = the family household
logy = the study of
interesting parallel to economy = management of the household many principles in common – resources allocation, cost-benefit ratios (household management)
definitions:
Haeckel (1870): “By ecology we mean the body of knowledge
concerning the economy of Nature - the investigation of the total relations of the animal to its inorganic and organic environment.” Andrewartha (1961): “The scientific study of the distribution and abundance of organisms.”
Krebs (1972):
“Ecology is the scientific study of the processes regulating the distribution and abundance of organisms and the interactions among them, and the study of how these organisms in turn
mediate the transport and transformation of energy and matter in the biosphere (i.e., the study of the design of ecosystem structure and function).”
The goal of ecology is to understand the principles of operation of natural systems and to predict their
ECOLOGY is the study of relationships among organisms and between organisms and the physical environment.
These relationships influence many aspects of the natural
world, including the distribution and abundance of organisms, the variety of species living together in a place, and the
Ecosystem:
An ecological community and its local,
nonbiological community. An ecosystem is the
minimum system that includes and sustains life.
It must include at least ………..
It must include at least an autotroph, a
decomposer, a liquid medium, a source and sink
of energy, and all the chemical elements required
by the autotroph.
Environment: All factors (living and nonliving) that actually affect an individual organism or population at any point in the life cycle.
Environment is also sometimes used to denote a certain set of
circumstances surrounding a particular occurrence (environments of deposition, for example ph and the decomposer).
Environmentalism: A social, political, and ethical movement concerned with protecting the environment and using its resources wisely.
Biosphere: part of a planet where life exists.
Community: a set of interacting species that occur in the same
place (sometimes extended to mean a set that interacts in a way to sustain life).
Population: A group of individuals of the same species living in the same area or interbreeding and sharing genetic information.
Habitat: Where an individual, population, or species exists or can
exist. For example, the habitat of the Joshua tree is the Mojave Desert of North America.
Biome: A kind of ecosystem. The rain forest is an example of a biome; rain forests occur in many parts of the world but are not all connected to each other.
Niche:
(1) The “profession,” or role, of an
organism or species;
or
(2) all the environmental conditions under
Biological diversity: consisting of three components:
(1) genetic diversity— the total number of genetic characteristics; (2) species diversity; and
(3) habitat or ecosystem diversity—the number of kinds of
habitats or ecosystems in a given unit area. Species diversity in turn includes three concepts: species richness, evenness, and dominance.
Succession: The process of establishment and development of an ecosystem.
Sustainability: Management of natural resources and the
environment with the goals of allowing the harvest of resources to remain at or above some specified level, and the ecosystem to retain its functions and structure.
Humans are rapidly changing earth’s environment, yet we do not fully understand the consequences of these changes.
For instance, human activity has increased the quantity of nitrogen cycling through land and water, changed land
cover across the globe, and increased the atmospheric concentration of carbondioxide.
Changes such as these threaten the diversity of life on earth and may endanger our life support system. Because of the rapid pace of environmental change in the early twenty first century, it is imperative that we better understand earth’s ecology.
Why study ecology? Curiosity
Responsibility Nature as a guide
How to study ecology? What kinds of experiments do ecologists perform?
Observations Microcosms
Ecologists study environmental relationships ranging from those of individual organisms to factors influencing global-scale processes.
Physiological ecologists
Behavioral ecologists
Faced with the complexity of nature, ecologists have divided the field of ecology into subdisciplines, each of which focuses on one of the levels of organization.
Ecosystem Structure
1. Biotic Levels = living organisms a. Individual Organisms
b. Populations
2. Abiotic Components = nonliving portion of biosphere a. Lithosphere
b. Hydrosphere
Ecosystem Function
A. Individual Requirements, Tolerance Ranges and Limiting Factors
B. Habitat Specific Adaptations
1. marine ecosystems
2. freshwater ecosystems 3. terrestrial ecosystems
C. Feeding Strategies: herbivores, carnivores, omnivores, detritivores D. Production & Productivity
1. respiration vs production 2. gross vs net productivity
3. primary & secondary productivity
E. Trophic Levels and Food Webs: producers consumers decomposers F. Pyramids of Numbers and Biomass
G. Biogeochemical Cycles
H. Energy Flow & Trophic Structure factors that limit productivity ecological efficiency and the "10% rule" length of food chains
I. Interactions: all organisms interact with other organisms in various
ways
1. Individual Interactions:
a. symbioses: mutualism commensalism parasitism b. predator / prey relationships
c. competition
i. intraspecific competition ii. interspecific competition
2. Population level interactions (Population Ecology) fluctuations in populations and genetic variation immigration and emigration
isolation and evolution local extinctions
3. Community level interactions (Community Ecology) concept of the niche foraging theory community structure
Energy flows in ecosystems
Energy flows through an ecosystem in one direction, from primary producers to consumers!
Food chain – series of steps in which organisms transfer energy by eating and being eaten.
